Question 5.13

People tell me my Message-IDs are not correct, why
aren't they and how to fix it?

Answer

The message-ID is an unique identifier for messages you
send. To make it unique, Gnus need to know which machine
name to put after the "@". If the name of the machine
where Gnus is running isn't suitable (it probably isn't
at most private machines) you can tell Gnus what to use
by saying:

(setq message-user-fqdn "yourmachine.yourdomain.tld")

in ~/.gnus.el. If you use Gnus 5.9 or earlier, you can use this
instead (works for newer versions as well):

If you have no idea what to insert for
"yourmachine.yourdomain.tld", you've got several
choices. You can either ask your provider if he allows
you to use something like
yourUserName.userfqdn.provider.net, or you can use
somethingUnique.yourdomain.tld if you own the domain
yourdomain.tld, or you can register at a service which
gives private users a FQDN for free.

Finally you can tell Gnus not to generate a Message-ID
for News at all (and letting the server do the job) by saying